1. Technical Field
The invention relates to a carrier for electrostatic image development, an image-forming method, and an image forming apparatus.
2. Background
Process for making image information visable via an electrostatic latent image, such as electrophotographic processes are currently used in various fields. In electrophotographic processes, an electrostatic latent image formed on a photoreceptor is developed with a developer containing a toner by charging and exposing, and the image is then made visable by transferring and fixing. The developers used in development include two-component developers, consisting of a toner and a carrier, and mono-component developers, such as magnetic toners in which a toner is used alone. The two-component developers, in which a carrier has the functions of agitating, conveying and charging the developer, i.e., functions different from that of the developer, have many advantageous characteristics and are currently widely used. In particular, developers containing a resin-coated carrier are superior in charge-controlling efficiency and allow easier improvements in environmental dependency and storability. For example, a cascade method has long been used for development, but recently a magnetic brush method, using a magnetic roll as a means of conveying the developer, is mainly used.
On the other hand, a so-called toner-reclaiming system, of feeding the toner recovered in cleaning as reused toner (hereinafter, referred to as “recycled toner”) back into the developing device and reusing the toner as the developing toner, is attracting attention recently from the viewpoints of cost, energy conservation, and environmental safety, and toner-reclaiming systems with improved image quality by the addition of an external additive with a particular particle diameter and numerical ratio are known.
A method of controlling the shape and electrostatic properties of the toner in a toner-reclaiming system is also proposed. By the method, it is possible to prolong the usable period because of the improvement in mixing between the recycled toner and the carrier, due to an improvement of carrier fluidity, and also possible to prevent in-machine staining because of an increase in adhesiveness between the toner and the carrier by electrostatic force.